Organ portamento system



April'9, 1968 R. w. BULL ETAL 3,376,776

ORGAN PORTAMENTO SYSTEM Filed June l5, 1965 N0, W u@ ww bo, m% WM Wb Vibrato ordinarily is applied ject, of course,

United States Patent O Filed June 15, 1965, Ser. No. 464,044 11 Claims. (Cl. 84-1.24)

This invention relates to electrical organs, and particularly to a portamento system to be used therewith or therein.

One of the objects of the present invention is to provide a novel partamento system which automatically drops the pitch of an organ approximately a semitone, and then causes the frequency to rise or slide up to the nominal tuned level over an appreciable time interval.

Another object is to provide a novel portamento system of the type indicated above which is automatic in operation and in which the amount of the portamento effect depends upon the number of keys which are played simultaneously up to some predetermined limit.

Still another object is to provide a novel portamento system which temporarily overrides the normal vibrato with a portamento effect and restores the vibrato as the frequency rises to normal.

Yet another object .of this invention is to provide a novel portamento which, when in operation, has little or no effect upon the pitch of the instrument if only one key is played, which has an appreciable effect if two keys are played simultaneously, and which can have a progressively greater effect if more keys are played simultaneously, up to some predetermined limit.

One rather conventional scheme used in the design of electric organs is to provide master electronic ,oscillators for each of the twelve notes of the top octave, and to use groups of cascaded frequency dividers for supplying the lower octaves from the twelve master oscillators.

to such instruments by providing a low frequency oscillator of some sort which gives an oscillatory signal at a frequency of about seven cycles per second, and then applying this oscillatory signal to the twelve master oscillators in such a manner as to shift the nominal oscillating frequency of the oscillators cyclically upwardly and downwardly relative to the nominal frequency at the virbato rate.

The present invention is concerned with the provision of a portamento system to be used in conjunction with oscillatorsfor instance, master oscillators-, including their vibrato system of the type mentioned above, for the purpose of providing additional signal animation.

Some musical instrumentsthe Hawaiian guitar is an exampleare frequently played in such manner as to cause a nete or a chord to be struck somewhat below the nominal pitch of the instrument, the instrumentalist f then causing the pitch to slide In general, the portamento nounced when two or simultaneously.

The present invention simulates this Hawaiian guitar effect and other effects of a generally similar nature, in that when keys are played upon the organ one at a time, only the nominal frequency is present along with any vibrato which may be provided. When two keys are played simultaneously, an effective portamento effect is produced which temporarily replaces the vibrato; that is, when the two notes are played together, their instantaneous sound is slightly flat, and the pitch thereafter ,gradually rises to the true pitch and remains at this true pitch, subto whatever vibrato effect is selected.

upwardly to the true pitch. effect is made more promore strings are played When three or more keys are played simultaneously, the portamento effect is somewhat greater in that the notes, when struck, are sounded flat initially by a greater amount-preferably up to about a semitone-, and then rise in pitch back to their nominal frequencies. This is accomplished automatically in that it is not necessary to move a foot pedal or other manually actuated control in order to accomplish the portamento effect.

A preferred embodiment which may be considered representative of the invention is illustrated in the accompanying drawing i-n which the single figure is a diagrammatic representation of the portamento system, including its connection to a representative oscillator which may be one of the twelve master oscillators previously mentioned.

In the drawing one of the master oscillators is shown near the bottom. In consists of an NPN transistor y10 having its base connected through a capacitor 12 to one end of an inductance 14, the other end of which is grounded. An intermediate tap on the inductance is connected through a resistor 16 to the transistor emitter. A capacitor 18 and resistor 20 are connected in parallel across the coil 14. The collector is connected to a 15 volt supply indicated by the terminal at 22 by way of resistor 24. The collector lead is also connected through a capacitor 26 and a set of contacts 28 operated by the .organ playing key to a signal output terminal 30, which in turn is connected to whatever control and output and speaker system the organ has. The signal is also taken from the collector by way of the lead 32 to whatever frequency divider supplies the next successively lower octave. Since these frequency dividers form no part of the present invention and may be conventional, they are not shown.

The variable vibrato voltage from the vibrato oscillator (not shown), which has the purpose of producing the vibrato effect, is introduced to the terminal 34. This terminal is connected through a vibrato on-off switch 36 and by way of a lead 38 and resistor 40 to the movable member 42 of a vibrato control switch. When this switch is thrown in one direction-labeled, for instance, Vibrato Normal-, it engages a contact 44 connected to the lead 46. When the switch blade 42 is thrown in the other direction indicated by the notation Vibrato Small, it engages contact 48 which is connected to the lead 46 by way of a resistor 50'. The contact 48 is also connected through a resistor 52 t0 a l5 volt terminal 54.

The lead 46 previously mentioned is connected to ground through capacitor 56, and in turn to each of the master yoscillators by way of individual bias resistors, fo-ur of which are shown at 68, while the identical fifth, 70, is connected to the base of the oscillator transistor lll.

The operation of the oscilla-tor and the vibrato portion of the circuit so far described is well understood and needs no special description Ibeyond stating that the frequency of operation of the oscillator 10V varies as a function of the voltage applied to the base within a considerable range; that is, the frequency rises with an increase in voltage in the line 46, and this voltage varies according to the output of the vibrato oscillator connected to the terminal 34, providing, of course, that the vibrato switch 36 is in the closed position. In other words, the alternating voltage from the terminal 34 is superposed upon the l5 Volt D.C. voltage supplied to the terminal 54.

The Vibrato Normal-Vibrato Small switch 42, in the Vibrato Small position, interposes the resistor 50v in the vibrato alternating current circuit, thereby reducing the strength of the alternating signal relative to the D.C. potential as compared with the situation which prevails when this switch is in the Vibrato Normal position.

The automatic portamento portion of the circuit is essentially that shown at the upper portion of the diagram and is constructed around a pair of NPN transistors 72 and 74. Toward the left of the drawing, a 3-volt lead is indicated lat 76. This lead is connected through a plurality of resistors 7S, each of lwhich is connected through a set of contacts 80, to a common bus 82. Contacts 80 are representative of a group of individual key contacts, one set for each of the playing keys. In other words, when a playing key is actuated, it closes one of the keying contacts 80, thereby connecting the 3-volt lead 76 through a -resistor 7 8 to the bus 82, |and substantially simultaneously actuation of the playing key closes another contact, which is represen-ted by the Contact set 28, thereby connecting the appropriate oscillator to the output circuit.

It will be appreciated that the contact set 28 is not necessarily connected to one of the twelve master oscillators of the type shown. 1t may be connected instead, as is well understood, to the output of one of the frequency dividers which is fat some position down the cascade with one of the master oscillators at the high frequency end.

Although there may be as many contacts 80 and resistors 78 as there are playing keys, it will be appreciated that it may be convenient to arrange a pattern of duplication of 4the resistors 78 for groups of keys in the interest of cost saving. This refinement, however, forms no part of the present invention, and so far as an understanding of this invention is concerned, it may be assumed that there can be a contact 80 and a resistor 78 for each of the playing keys covering the key span to which the portamento system is applied.

The bus 82 is connected to ground through a resistor 84 and diode 86 in parallel, the diode 86 being oriented t0 pass current when the potential of the lead 82 is sufficiently above ground, about .6 v. The lead 82 is also connected through capacitor 88 to the base of transistor 72, which is also connected to the emitter of transistor '74, and to ground through a resistor 90. The e-mitter of transistor 72 is connected to ground through resistor 91.

A l-volt terminal 92 is connected through a resistor 94, variable -resistor 96, and resistor 97 in series, to the base of transistor 74, this base also being connected to ground through a resistor 98. The common point between resistor 94 and variable resistor 96 is also connected to ground through a pair of diodes 100 in series. These diodes are both oriented to pass current when the common point between resistors 94 and 96 is suiciently above ground, about 1.2 v. The two diodes 100l are used in series to compensate for temperature variation and to maintain a potential thereacross of -about 1.2 v. The collector of transistor 74 is connected to ground through resistor 104 and to a lS-volt voltage supply terminal 106 by way of resistor 108, and the collector of transistor 72 is connected through an on-oif portamento switch 102 to the vibrato lead 38 previously mentioned.

Suitable circuit constants for the particular circuit illustrated are as follows. Transistors are of the silicon planar type-2N27l2, for instance-and diodes are typical silicon junction type.

Resistors are as follows:

16 ohms 82 91 do 100 84 do 150 78 and 97 1K 40 1.2K 2.2K 96 (rheostat) 3K 94 4.7K 50 and 52 6.8K 24 and 90 10K 104 and 108 12K 1 56K 68 and 70 180K lAt 1760 c.p.s.

Capacitors are as follows: f

lAt 1760 c.p.s.

As noted, some of the constants will vary depending upon the frequency. For completeness of description, they have been given typical values suitable for 1760 c.p.s., which is two octaves above the A-440 standard. Of course these and other variations may be made in the circuit within the understanding of a person skilled in this art.,

When a key is played, its contact set connects the 3-volt lead 76 to the -bus 82 which is grounded through resistor 84. The voltage on bus 82 therefore rises to a low level, since R78 has a value of 1K and R34 a value of ohms. The gate transistor 72 is biased by way of the clamp transistor 74 to ignore this small voltage increase coupled through capacitor 88 so that conduction through the gate 72 does not occur. lf two keys are played, current is supplied through two of the resistors 78 in parallel, and the increase in voltage on the bus 82, therefore, is higher than if one key is played. Similarly, if three or more keys are played, the voltage increase at bus 82 is still greater, up to the limit set by the diode 86.

The capacitor 88 and resistor 90 differentiate any step increase in voltage at the bus 82 into a pulse with a sharp rise time and slow decay, which, if sufficiently positive, will cause conduction through the gate transistor 72. The transistor 72, therefore, draws collector current from the terminal 54 by way of resistors 52 and 40, and through 50 if switch 42 is in the Vibrato Normal position. This superposes a drop in voltage and load impedance upon the vibrato signal in line 46, which in turn drops the frequency of the oscillator 10. As the capacitor 88 discharges, the potential of line 46 rises so as to reverse the effect and restore the normal oscillator frequency and vibrato. When whatever playing keys being held are released, the potential on lead 82 drops, and the capacitor 88 is quickly restored to the starting condition by conduction through the clamp 74. More specifically, when contacts 80 are closed, the positive pulse thus produced turns the clamp 7.4 off and capacitor 88 is charged through a high impedance; when contacts 80 are opened, the negative going pulse turns the clamp on and quickly discharges capacitor 88. Thus, if the vibrato switch 36 is in the on position, vibrato will normally be present until two or more keys are played together. 1f the switch 102 is on when two or more keys are played, the frequency of the oscillators will drop and the vibrato effect will be largely or completely extinguished. The frequency thereafter gradually rises and the vibrato reappears. lf the vibrato switch 36 is in the off position, the same portamento effect occurs except that no vibrato will be present when the `frequency of the oscillators returns to their nominal frequency. The position of the Vibrato Normal-Vibrato Small switch 42-44-48 simply estab'- lishes the width of the vibrato swing, and, regardless of the position of this switch, the portamento effect overrides the vibrato in the manner discussed above, depending of course upon the position of the portamento switch 102.

I will be noted that an important aspect of this invention is that the portamento effect is automatic, and that by a selection of circuit parameters the circuit can be made to respond such that no portamento effect is produced when a single key is played, this effect being pro'- duced only when two or more keys are played together, and that a limit can be placed upon the extent of this response; that is, a portamento eifect can be produced if two keys are played together, and still more effect if three keys are played together, but no additional portamento effect needs to be produced if still more keys are played if this is the desired result, since the diode 86 limits the potential that can exist on the line 82.

Although this invention has been explained on the basis of additional playing keys closing additional contacts to produce the portamento effect, the same circuit can be used with what is commonly known as a second touch system. In this system, as the playing key is partially depressed, it closes a contact, and if it is depressed further, it closes a second contact. Such a system enables the musician to play in a manner which actuates only the first set of contacts, or, if he wishes to do so, he may push the keys down an additional step so as additionally to actuate the second set of contacts. Various effects can be obtained in conjunction with second touch contacts, and it is not the purpose of this invention to provide a specific second touch arrangement. It will be appreciated, however,`that the first contact to close in a second touch system can be one of the contacts 80, and the second set of contacts to close in such a system can be another set of the contacts 80, so that if a key is partially depressed, one set of contacts 80 will be engaged without producing a portamento, but that if the key is depressed further, the portamento effect will be produced when the second touch contact is closed. With such a system, the musician can obtain the portamento while playing a single key, if desired. In other words, so far as the portamento circuit is concerned, it reacts in the same manner whether the two contacts, which are closed, are in a second touch system, .or whether they are actuated by separate keys. Also, of course, the circuit is indifferent to whether three or four contacts played together represent three or four separate keys or two keys having second touch contacts. If such a second touch system is desired, it is simply necessary to consider the top two switches 80 as being actuated in succession by one playing key, the next two contacts 80 in succession by another playing key, and so on.

An inherent advantage of this .automatic system is that the 'recovery time is finite and can be as desired. Thus, if two keys are played simultaneously, a certain rise in potential on line 82 will occur to give a :certain amount of portamento. If the twokeys are played in quick succession, the first being held while the second is pressed, the same potential will be established on line 82, but the portamento will be less, because part of the charge on the capacitor 88 established by playing the first key will have lleaked off through resistor 90 before the second key is played. If the two keys are played detached or in slow succession, or if, after a normal portamento is produced, a plurality of keys are played suddenly, no additional portamento will result. This gives the musician a considerable degree of touch responsiveness which is musically useful.

It will be .appreciated that this invention has been described in conjunction with a specific circuit in which values have been given as an aid to understanding the circuit, but that variations can be made without departing from the scope and spirit of the invention, and that the scope of the invention is to be measured by the scope of the following claims.

Having described our invention, what we claim as new and useful and desire to secure by Letters Patent of the United States is:

1. A portamento system for a musical instrument of the keyboard type comprising, means providing a group of tone signal sources of the type in which the frequencies supplied by the sources vary with an electrical condition existing at a terminal common to all of the sources in said group, means for establishing a nominal electrical condition at said terminal, circuit means connected to said terminal and adapted when actuated for changing the electrical condtion at said terminal away from said nominal condition abruptly in one direction and then returning the condition at said terminal slowly to said nominal electrical Cil condition, said circuit means having a control connection adapted to actuate said circuit means when a condition at said control connection is shifted in one direction from a nominal condition by more than a certain amount, said circuit means being deactivated when said control connection is at the last said nominal condition or a condition which is shifted from the last said nominal condition by no more than the said certain amount, circuit means including a mechanism actuated by a plurality or playing key actuated switches connected to said control connection and adapted to shift the condition at said control connection by no more than said certain amount when a single one of any of said switches is actuated but to shift the condition at said control connection by an amount which is more than said certain amount if a plurality of said switches are actuated together.

2. A portamento system for a musical instrument of the keyboard type comprising, means providing a group of tone signal generators of the type in which the frequencies generated vary with the potential applied to a terminal common to all of the generators in said group, means for supplying a cyclically varying vibrato potential to said terminal, circuit means connected to said terminal and adapted when actuated for overriding the vibrato potential and changing the potential at said terminal abruptly in one direction and then returning the potential at said terminal slowly to said vibrato potential, said circuit means having a control connection adapted to actuate said circuit means when the potential at said control connection is shifted in one direction from a nominal potential by more than a certain amount, said circuit means being deactivated when said control connection is at the last said nominal potential or a potential which is shifted from the last said nominal potential by no more than the said certain amount, circuit means including a plurality of playing key actuated switches connected to said control connection and adapted to shift the potential at said control connection by no more than said certain amount when a single one of any of said switches is actuated but to shift the potential at said control connection by an amount which is more than said certain amount if a plurality of switches are actuated together.

3. A portamento system for a musical instrument of the keyboard type comprising, means providing a group of tone signal generators of the type in which the frequencies generated vary with the potential applied to a terminal common to all of the generators in said group, means for supplying a cyclically varying vibrato potential to said terminal, a pulse producing circuit connected to said terminal and adapted when actuated for supplying a pulse for changing the level of the varying vibrato potential at said terminal abruptly in one direction and then returning the potential at said terminal slowly to said varying vibrato potential, said pulse circuit having a control connection adapted to actuate said pulse circuit when the potential at said control connection is shifted in one direction by more than a certain amount from a nominal potential, said pulse circuit being deactivated when said control connection is at the last said nominal potential or a potential which is shifted from the last said nominal potential by no more than the said certain amount, circuit means including a plurality of playing key actuated switches connected to said control connection and adapted to shift the potential at said control connection by no more than said certain amount when a single one of any of said switches is actuated but to shift the potential at said control connection by an amount which is more than said certain amount if a plurality of switches are actuated together, and means for conditioning the first said circuit means for repeat operation upon deactuation of actuated switches.

4. A portamento system for a musical instrument of the keyboard type comprising, means providing a group of tone signal generators of the type in which the frequencies generated vary with the potential appled to a terminal common to all of the generators in said group, means for supplying a nominal potential to said terminal, a pulse producing circuit including a capacitor discharge and gate circuit connected to said terminal and adapted when actuated for supplying a pulse for shifting the potential at said terminal abruptly in one direction away from said nominal potential and then returning the potential at said terminal slowly to said nominal potential, said pulse circuit having a control connection adapted to actuate said pulse circuit to supply a lpulse when the poential at said control connection is shifted in one direction by more than a certain amount from a nominal potential, said pulse circuit being deactivated so as not to supply a pulse when said control connection is at the last said nominal potentialor a potential which is shifted from the last said nominal potential by no more than the said certain amount, circut means including a plurality of playing key actuated switches connected to said control connection and adapted to shift the potential at said control connection by no more than said certain amount when a single one of any of said switches is actuated but to shift the potential at said control connection by an amount which is more than said certain amount if a plurality of switches are actuated together, and means for conditioning the rst said circuit means for repeat operation upon deactuation of actuated switches.

5. The combination called for in claim 1 including means for limiting to a certain value the maximum condition shift at said control connection regardless of the number of key switches actuated together.

6. The combination called for in claim 2 including means for limiting to a certain value the maximum potential shift at said control connection regardless of the number of key switches actuated together.

7. The combination called for in claim 3 including means for limiting to a certain value the maximum potential shift at said control connection regardless of the number of key switches actuated together.

8. The combination called for in claim 4 including means for limiting to a certain value the maximum potential shift at said control connection regardless of the number of key switches actuated together.

9. The combination called for in claim 1 in which the means for establishing the first said nominal electrical condition establishes a cyclically variable condition at a vibrato rate.

10. A portamento system for a musical instrument of the keyboard type comprising, means providing a group of tone signal sources of the type in which the frequencies supplied by the sources vary with an electrical condition existing at a terminal common to all of the sources in said group, means for establishing a nominal electrical condition at said terminal to provide nominal frequencies, circuit means connected to said terminal and adapted when actuated for changing the electrical condition at said terminal away from said nominal condition abruptly in one direction and then returning the condition at said terminal slowly to said nominal electrical condition, said circuit means having a control connection adapted to actuate said circuit means when a condition at said control connection is shifted in one direction from a nominal condition by more than a certain amount, said circuit means being inactive when said control connection is at the last said nominal condition or a condition which is shifted from the last said nominal condition by no more than the said certain amount, circuit means including a mechanism actuated by a plurality of playing key actuated devices connected to said control connection and adapted to shift the condtion at said control connection by an amount which depends upon the number of said devices actuated together, but not in excess of a certain maximum amount of shift in the last said condition, said certain maximum amount of shift being excess of said certain amount of shift.

11. The combination called for in claim 10 in which the means for establishing the first said nominal electrical condition establishes a cyclically variable condition at a vibrato rate. v

References Cited UNITED STATES PATENTS 12/1959 Anderson 84-l.24 3/1960 Hanert SLi- 1.25 84-l.25 

1. A PORTAMENTO SYSTEM FOR A MUSICAL INSTRUMENT OF THE KEYBOARD TYPE COMPRISING, MEANS PROVIDING A GROUP OF TONE SIGNAL SOURCES OF THE TYPE IN WHICH THE FREQUENCIES SUPPLIED BY THE SOURCES VARY WITH AN ELECTRICAL CONDITION EXISTING AT A TERMINAL COMMON TO ALL OF THE SOURCES IN SAID GROUP, MEANS FOR ESTABLISHING A NOMINAL ELECTRICAL CONDITION AT SAID TERMINAL, CIRCUIT MEANS CONNECTED TO SAID TERMINAL AND ADAPTED WHEN ACTUATED FOR CHANGING THE ELECTRICAL CONDITION AT SAID TERMINAL AWAY FROM SAID NOMINAL CONDITION ABRUPTLY IN ONE DIRECTION AND THEN RETURNING THE CONDITION AT SAID TERMINAL SLOWLY TO SAID NOMINAL ELECTRICAL CONDITION, SAID CIRCUIT MEANS HAVING A CONTROL CONNECTION ADAPTED TO ACTUATE SAID CIRCUIT MEANS WHEN A CONDITION AT SAID CONTROL CONNECTION IS SHIFTED IN ONE DIRECTION FROM A NOMINAL CONDITION BY MORE THAN A CERTAIN AMOUNT, SAID CIRCUIT MEANS BEING DEACTIVATED WHEN SAID CONTROL CONNECTION IS AT THE LAST SAID NOMINAL CONDITION OR A CONDITION WHICH IS SHIFTED FROM THE LAST SAID NOMINAL CONDITION BY NO MORE THAN THE SAID CERTAIN AMOUNT, CIRCUIT MEANS INCLUDING A MECHANISM ACTUATED BY A PLURALITY OR PLAYING KEY ACTUATED SWITCHES CONNECTED TO SAID CONTROL CONNECTION AND ADAPTED TO SHIFT THE CONDITION AT SAID CONTROL CONNECTION BY NO MORE THAN SAID CERTAIN AMOUNT WHEN A SINGLE ONE OF ANY OF SAID SWITCHES IS ACTUATED BUT TO SHIFT THE CONDITION AT SAID CONTROL CONNECTION BY AN AMOUNT WHICH IS MORE THAN SAID CERTAIN AMOUNT IF A PLURALITY OF SAID SWITCHES ARE ACTUATED TOGETHER. 